During the final stages of plumbing, a test must be conducted to ensure the integrity of the plumbing system. This requires charging the system such that it becomes pressurized, during which time the plumber looks for leaks. The system must be closed in order to make the assessment. Once the integrity is assured, the means for plugging the system is removed.
What is required is a simple, inexpensive seal that can withstand the pressures needed to test plumbing installations, while being readily removable after the testing is completed.